He was the saxophonist at Lady Gaga's recent Music Video 'The Edge of the Glory'-which is the last time we saw him.
The New York Times said Clemons' death was confirmed by a spokeswoman for Springsteen. Reuters could not immediately confirm the reports.
Clemons, dubbed the "Big Man," started working with Springsteen in 1971 and was a charter member of the backing group that came to be known as the E Street Band.
His gritty, evocative saxophone solos powered such notable Springsteen songs as "Born to Run," "Jungleland," "Prove It All Night," "Tenth Avenue Freeze Out," and "Badlands."
On stage, Clemons proved a worthy foil for Springsteen and his bandmates. In a 1975 concert review, Rolling Stone said Clemons betrayed an "ominous cool" in contrast to guitarist Steven Van Zandt's "strange hipster frenzy."
"Clarence was the big black saxophone player who completely represented the tradition of rock 'n' roll and R&B," Van Zandt told Britain's Mojo magazine in 2006.
Alongside Van Zandt, Clemons personified the E Street Band, and he took it hard when Springsteen broke up the group for a decade in 1989. But by then, Clemons was being used less in the studio. On stage, he was often reduced to playing tambourine or engaging in crowd-pleasing theatrics, like kissing Springsteen during the live staple "Rosalita (Come Out Tonight)."
He also dabbled in acting, enjoyed a solo hit single with Jackson Browne, 1985's ""You're a Friend of Mine," toured with Ringo Starr and even played on two tracks on pop singer Lady Gaga's new album.
Clemons' death came three years after organist Danny Federici, Springsteen's longest-serving musical partner, lost a three-year battle with cancer.
Clemons had been in ill health in recent years, suffering back and hip problems. He had double knee-replacement surgery in 2008, and walked for the first time in three months when Springsteen and the E Street Band played the Super Bowl early in 2009. The band's eight-month world tour that year was "pure hell," he told Rolling Stone earlier this year.
Clemons was born January 11, 1942 in Norfolk, Virginia, and played saxophone in high school where he was also a promising football player. A car crash ended his professional sporting dreams, and he went on to become a social worker, family man and barroom rocker.
His first meeting with Springsteen was auspicious. Clemons had heard about a hot young rocker on the Asbury Park, New Jersey, scene, and walked into one of his club shows on a bitterly windy night. A gust of wind ripped the door from his hand, and it flew down the street. All eyes turned to Clemons, and Springsteen readily agreed when he asked to sit in with him.
"When I first walked on that stage and hit the first note, I saw things that are happening today, then," he told Reuters in 2009. "I knew that he (Springsteen) was what I was looking for and I was what he was looking for to take that next step to the big time. It was just love, man, at first sight."
During sessions for Springsteen's 1975 breakthrough "Born to Run," Clemons spent 16 hours recording his solo on "Jungleland," the nine-minute track that closes the album.
"Creating is like religion," Clemons said later of the marathon session. "I was willing to relinquish myself to him (Springsteen). I've had people say to me, 'That sax solo saved my life.' So I did my job."
Clemons was used more sparingly in later years as Springsteen opted to emphasize the guitars (1978's "Darkness on the Edge of Town") or recorded largely solo (1982's "Nebraska" and 1987's "Tunnel of Love."
He still brought fervor to later-era songs like the hit single "Dancing in the Dark" and "Land of Hope and Dreams, but "over time his role in the band has become more symbolic than musical," author Jimmy Guterman wrote in his 2005 Springsteen biography "Runaway American Dream."
In 2009 he published his memoir, "Big Man: Real Life and Tall Tales," co-written with his friend Don Reo.